As the technology continues to progress, the technology of the backlight for illuminating a liquid crystal display apparatus also continues to develop. The typical and conventional backlight module of the existing liquid crystal display apparatus utilizes a cold cathode fluorescent lamp (CCFL) as a light source. However, as known to the skilled in the art, that the disadvantages of a CCFL backlight module include poor color reproduction capability, low luminous efficiency, high discharging voltage, poor discharge characteristics at low temperature, and a prolonged warming up time to reach stable grey scale. Currently, the technology of using an LED backlight module has been developed.
However, in an existing driver circuit of an LED backlight module, such as shown in FIG. 1, a constant current driver circuit 13 outputs a signal (i.e. driving signal) to a gate of a MOS transistor Q of a boosting circuit 11. When the MOS transistor Q operates, an internal equivalent direct current resistance (DCR) is generated, and the value of the DCR is reduced with the increase of the voltage between the gate and the source of the MOS transistor Q. Once the MOS transistor Q is turned on, an electric current flow through the gate and the source, and the MOS transistor Q will consume power due to the existence of the equivalent direct current resistance (DCR). In light of this, the lifespan of the MOS transistor Q decreases resulted from the increase of the temperature, and thereby the lifespan of the boosting circuit also decreases due to the increase of the power consumption.